The field of the present invention is systems for dispensing carbonated beverages and the cooling of the supplied beverages.
Commercial establishments with drink dispensing systems employ a variety of mechanisms to create and dispense carbonated and noncarbonated beverages. Such systems generally associated with what may be termed fountain service typically generate the carbonated water from carbon dioxide and service water. The beverage ingredients, water, carbonated water and syrups, are then mixed at faucets upon demand. Mixing spouts associated with valves forming the faucets are disclosed in U.S. Pat. No. 4,928,854 and U.S. patent application Ser. No. 09/281,688, filed Mar. 30, 1999, the disclosures of which are incorporated herein by reference. In commercial systems, the dispensers are conveniently located proximate to an ice storage bin. However, the ingredients are frequently stored at a distance from the dispensing equipment.
In bar service, as opposed to fountain service, bar gun systems are more frequently employed. Such guns include a long flexible sleeve with conduits therein. The conduits are full of various ingredients for supply on demand through valves to a spout. Because of limited space, fluids in these tubes are not insulated. Bars employ a number of configurations from remote location of the supply to storage under the bar. Commonly, an ice bin is located near the bar gun as a further source of drink ingredients.
As an industry standard, it is preferred that the dispensing of beverages be at a lower temperature even though the beverages are typically poured over ice. This is particularly true of carbonated beverages where the amount of carbon dioxide which can be held by the liquid varies inversely with the temperature. The industry would like to keep carbonated water at the fountain to as close to 33xc2x0 F. as possible and always below 40xc2x0 F. Such systems conventionally use either a heat transfer system associated with the proximate ice storage bin or a mechanical refrigeration system for keeping the ingredients cold. Lines and tanks are frequently insulated to assist in keeping the chilled ingredients cold pending distribution.
In heat transfer systems, ice storage bins are provided with a cold plate forming the bottom of the bin. Coils are cast within the cold plate of the ice storage bins to effect heat transfer between ice within the bin and beverage ingredients flowing through the coils. Thus, certain of the various fluids combined to make beverages are chilled through these coils for distribution as beverage is drawn from the system. Beverage dispensing systems with a cold plate system now account for an estimated seventy to eighty-five percent of the fountain service dispensers used in the United States today. Bar gun systems also have employed cold plates in ice storage bins adjacent the dispenser for chilling carbonated water. A line from the cold plate extends to the gun parallel to syrup lines.
These cold plates can vary in size, depending on the desired number of soft drinks to be dispensed through a maximum use period. The plates have many feet of stainless steel tubing formed in very tight coils that are cast inside a block of aluminum. The aluminum block provides a heat exchange container. High capacity cold plates can be from two to five inches thick and of various sizes depending on the size of the ice storage bin and the cooling requirements. Bar gun systems typically require smaller cold plates than in-store drink dispensing systems.
There are separate cooling paths for carbonated water, plain water and each flavor of syrup when all are cooled. The carbonated water heat transfer systems can employ a single or double coil circuit in series for cooling in high demand systems. The coils for carbonated water can be as long as seventy feet while the syrup coils are generally much less, often twenty to forty feet. Further, the tubing making up the syrup coils is frequently xc2xcxe2x80x3 ID while the tubing for the carbonated coils is larger, from {fraction (5/16)}xe2x80x3 to xe2x85x9cxe2x80x3 ID. The tubing is tightly arranged within the cold plate with tight bends.
The length of tubing and the circuitous coiling of the tubing in such cold plates can create a significant pressure drop in the flow therethrough. The pressure drop can be of concern to designers where multiple sets of dispensers are used with passes through multiple coil circuits in series. An excessive pressure drop can adversely affect the operation of the system during busy times as a certain level of pressure is demanded at the dispensers to insure adequate throughput. The industry typically wants a minimum of 40 psi at the back of each faucet for carbonated water and a minimum of 15 psi for syrup. At the same time, excessive carbonation resulting from high pressure in the carbonator can create a foaming problem. Excessive pressure drop through successive coil circuits can, therefore, require substantial pressure prior to the cooling process to achieve the required minimum pressure at the faucet. If carbon dioxide is introduced prior to the pressure drop under such conditions, excessive carbonation can result.
Cold plates currently employed are disclosed in U.S. Pat. Nos. 4,651,538, 5,419,393 and 5,484,015, the disclosures of which are incorporated herein by reference. These cold plates are much heavier in design than earlier such devices. The cold plate systems have increased in size as greater and greater volumes of beverage are consumed. Typical soft drink volumes have grown from six ounces in the past to as much as sixty-four ounces today. Depending on the design, even greater pressure drops can be experienced.
The performance of such systems employing a cold plate naturally depends on the rate at which the beverages are being dispensed. So long as there is ice in the ice storage bin, adequate cooling is typically accomplished under high volume flow. However, during periods when there is low demand, the stagnated liquids between the cold plate and the dispensers or bar gun can experience a temperature rise, referred to in the industry as a casual drink warm-up, as there is no further contact with the cold plate.
A prior cold plate system avoiding the issue of over carbonation and excessive plate size employed a cold water system which circulated through a cold plate. Upon demand, cold water was delivered to an on-the-fly carbonator after leaving the cold water system and then to the faucet. The cooling system was, therefore, a source of cold water to the carbonated beverage dispensing system and did not operate within the dispensing system itself.
The mechanically refrigerated beverage dispensing systems are used to a lesser extent than cold plate units. Mechanical refrigeration is more expensive and requires more frequent service. The faucets of systems using such mechanical refrigeration are still typically mounted over an ice storage bin used for the drinks. Such ice storage is not used to cool the carbonated beverage and does not include a cold plate system when using mechanical refrigeration. Mechanical refrigeration systems typically circulate carbonated water to maintain an adequate reservoir of cooled supply. Even so, high volume flow can slowly tax the system with gradually increasing liquid temperatures with no recourse but to quit dispensing drinks rather than to just add more ice. When mechanical refrigeration systems fail, the system must be shut down pending repair rather than, again, just adding more ice.
Mechanically refrigerated cooling systems are principally employed with very high volume systems at substantial cost. Some disclosed systems are found in U.S. Pat. Nos. 3,011,681, 3,162,323, 3,215,312, 3,731,845, 3,813,010, 4,148,334, 4,304,736, 4,742,939 and 4,793,515, the disclosures of which are incorporated herein by reference.
Carbonated water is manufactured in stainless steel tanks varying in size from one quart to three or four gallons in commercial beverage dispensers. These tanks are generally pressurized at 60 to 110 psi by the carbon dioxide. The higher pressure requirements typically reflect higher water temperatures. Service water enters the tank as demanded. The level in the tank is controlled by a sensor and the supply is provided by an electric motor and pump assembly.
Systems can also employ water pressure boosters. Such boosters provide for a reservoir of pressurized water. They additionally may provide for a reservoir of carbonated water as well. Water pressure boosters can include a water chamber, a carbon dioxide pressurized or pressurized air chamber and a movable wall therebetween. The movable wall may be a bladder. The carbon dioxide pressurized chamber can also hold carbonated water with adequate liquid fill control. The boosters employ water pressure booster valves which respond to the amount of stored water in the water chambers. The valve directs water to the water chamber until a desired level is reached. Water is then directed to the carbonator. Both the booster and the carbonator can include switches to activate a supply pump for charging of the system. The booster and the carbonator functions accommodate a single supply pump and provide similarly pressurized carbonated and noncarbonated water to a beverage dispensing system. A booster combined with a carbonator is disclosed in U.S. Pat. Nos. 5,855,296 and 6,196,418, the disclosures of which are incorporated herein by reference.
In commercial systems, the carbonator is typically displaced from the dispensing system. The water is at ambient temperature and the carbon dioxide pressure is generally set at 90 psi to 100 psi. The volume of carbonation in the system is generally in the range of 5 to 6 volumes. As some carbonation is lost in the dispensing process, the initial level of carbonation before dispensing is typically higher than that in canned beverages. This overpressure accommodates the various conditions imposed by the dispensing system. However, the most problematic is the maintenance of low temperature within the beverage to be dispensed in order that stable carbonation can be maintained in the drink when dispensed. Extra pre-chillers and increased cooling coil footage have been employed to decrease the faucet temperature. Even so, the low volume casual drink usage remains problematic in cold plate systems.
The present invention is directed to drink dispensing systems employing dispensers served by circulating fluid circuits. Ice storage bins having cold plates and circulation pumps are arranged within the fluid circuits. Such circulating systems provide capacity in cold plate systems to dispense properly chilled beverages regardless of the rate of usage.
When multiple sets of dispensers and ice storage bins are employed, the fluid circuitry may provide series flow, parallel flow or a combination of the two between the multiple dispensing stations. Separate systems additionally can include noncarbonated water and sources of the various drink components.
Where very high dispensing flow is expected, return line backfill can also be provided to avoid pressure drops in the system. Pressure drops can result in carbon dioxide coming out of solution within the system. The increased capacity can be provided without increasing the flow capacity of the supply side of the circuit.
Accordingly, it is an object of the present invention to provide improved temperature maintenance in cold plate drink dispensing systems. Other and further objects and advantages will appear hereinafter.